1. Field of the Invention
This invention relates generally to sealed rotary drill bits as may be used, for example, for drilling large diameter blast holes in taconite deposits. It is more particularly directed to an improved seal that is operable intermediate a rotatable cutter cone disposed on a journal extending from the leg, or legs of a drill bit. In a sealed drill bit of the class with which my invention is concerned, it is necessary to prevent contaminants in the form of small particles of the materials into which holes are drilled from entering a complex array of bearing devices that are used to support the cutter cone on the journal under adverse conditions of high pressures, forces and heat and to prevent the loss of lubricant placed in and around such bearings intermediate the interior of the cutter cone and the journal.
2. Description of the Prior Art
The following is a list of prior art in the form of United States Letters Patent that relate, in one way or another, to the field of my invention:
______________________________________ U.S. Pat. No. Inventor Issued ______________________________________ 3,193,028 Radzimovsky July 6, 1965 3,251,634 Dareing May 17, 1966 3,656,764 Robinson April 18, 1972 3,866,695 Jackson February 18, 1975 3,921,735 Dysart November 25, 1975 4,140,189 Garner February 20, 1979 4,183,417 Levefelt January 15, 1980 ______________________________________
A consideration of the disclosures of the prior art set forth above will indicate a wide range of fields that have been proposed, stemming with a basic "O"-ring to complicated labryinth configurations.